The system of tunnels in Rome were constructed under Mussolini, but the planned subway system was never completed. The abandoned tunnels are now often used for the legal growth of mushrooms, but a strong odor had led police to investigate the tunnel and discover a large cannabis farm.

The drug haul has a street value of almost 3 million euros ($3.8 million), and is one of the biggest ever found by Italian police. A 57-year-old man who owns the farm has been arrested.